1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2012 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedbackon this Technical Report, please visit http:/www.sae.org/technical/standards/J2688_201204SURFACEVEHICLERECOMMENDEDPRACTICEJ2688 APR2012 Issued 2012-04 Parking B
5、rake Control Identification - Vehicles with Hydraulic Brake Systems and Automatic Transmissions RATIONALE There are several parking brake indication and control philosophies for hydraulic braked vehicles with a GVWR greater than 4540 kg (10 000 lb). For future vehicle and parking brake system design
6、s, this recommended practice is intended to be a guide for consideration. The implementation of this new recommended practice will reduce operator confusion and promote standardization in all hydraulic braked vehicles. This recommended practice is intended to supplement the SAE J915 Automatic Transm
7、issions - Manual Control Sequence recommended practice as it relates to the various parking brake indication options. Major vehicle manufacturers were surveyed and current practices were identified to assist in the development of this document. Where necessary or possible all current practices were
8、included in this document to allow for alternative methods to provide the specific functions. The task force recognized that both the “P” and “PB” indication options existed in current vehicle applications. The team evaluated the benefits and risks of both approaches and the following is a summary o
9、f the results. In conclusion it was decided to recommend the “PB” indication as the standard method. “PB“: o gives indication to the driver that the parking mechanism is a friction-based product that wears and can yield over timeo is different from a park pawl in that it can sometimes be released in
10、dependently by other manual means o may not be acceptable in Canada (French language and ISO complications) “P“: o minimizes confusion for driver (“why should he or she care how vehicle is held in park, as long as it is“) Besides the indication recommendations, a transmission parking pawl and a mech
11、anical friction parking brake should not be actuated with the same or single actuation device or method. Besides the operator not knowing which parking brake function is actually holding the vehicle, there can be binding and brake release sequence issues with having a single parking actuation functi
12、on. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2688 Issued APR2012 Page 2 of 7 1. SCOPE The scope and purpose of the SAE Recommended Practice is to provide standards for the control and ind
13、ication of parking brakes in hydraulic braked vehicles over 4540 kg (10 000 lb) GVWR. This recommended practice pertains to automatic transmission applications and supplements the SAE J915 recommended practice. This recommended practice does not address parking brake system performance. Parking brak
14、e system performance, both static and dynamic conditions, is the responsibility of the OEM vehicle manufacturer or manufacturers that modify the vehicle by adding special vocational required equipment (such as but not limited to outriggers, cranes, etc.). 2. REFERENCES 2.1 Applicable Documents The f
15、ollowing publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside
16、USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE J915 Automatic Transmissions - Manual Control Sequence SAE J2208 Park Standard for Automatic Transmissions 2.1.2 United States Government Federal Safety Standards Available from the Document Automation and Production Service (DAPS), Buil
17、ding 4/D, 700 Robbins Avenue, Philadelphia, PA 19111-5094, Tel: 215-697-6257, http:/assist.daps.dla.mil/quicksearch/.Motor Vehicle Safety Standard (FMVSS) No. 101 Controls and Displays Motor Vehicle Safety Standard (FMVSS) No. 102 Transmission Shift Position Sequence, Starter Interlock, and Transmis
18、sion Braking Effect Motor Vehicle Safety Standard (FMVSS) No. 105 Hydraulic Brake and Electric Brake Systems Motor Vehicle Safety Standard (FMVSS) No. 135 Passenger Car Brake Systems 2.1.3 European Economic Community (EEC) / United Nations Economic Commission for Europe (ECE) Regulations ECE Regulat
19、ions available from United Nations Economic Commission for Europe, Palais des nations, CH-1211, Geneva 10 Switzerland. Tel:41-0-22-917-12-34. www.unece.orgEEC Regulations available from Automotive Industry, European Commission, B-1049 Brussels Belgium, Tel: 32-2-299-96-96. www.ec.europa.eu.78/316/EE
20、C Controls and Displays 2.1.4 Government of Canada Motor Vehicle Safety Regulations Available from Transport Canada, 330 Sparks Street, Ottawa, ON K1A ON5, Tel: 613-990-2309, www.tc.gc.ca.Motor Vehicle Safety Standard (CMVSS) No. 101 Controls and Displays Copyright SAE International Provided by IHS
21、under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2688 Issued APR2012 Page 3 of 7 3. DEFINITIONS 3.1 TRANSMISSION PARKING PAWL A mechanical device incorporated in the transmission that when engaged locks the transmission from moving resulti
22、ng in the parking function. This device functions only when the vehicle is stopped (not moving) and does not provide dynamic braking performance. 3.2 MECHANICAL FRICTION PARKING BRAKE A dry friction drum or disc brake assembly commonly called the “parking brake” that is actuated to provide the holdi
23、ng forces to park the vehicle. These parking brakes can be utilized to meet special requirements for dynamic (vehicle moving) vehicle braking performance. 3.3 A keypad is a set of buttons or a pre-printed film surface arranged in a block or “pad“ which usually bear digits, symbols and alphabetical l
24、etters that represent the various transmission shift positions 3.4 SAAR Spring Applied and Air pressure Release actuator utilizing air pressure from the air brake system or a separate compressed air pressure source on the vehicle to release the parking brake. The parking brake is applied by releasin
25、g the pressure allowing the actuator spring to apply. 3.5 SAHR Spring Applied and Hydraulic pressure Release actuator utilizing hydraulic pressure from the hydraulic braking system or a separate hydraulic pressure source on the vehicle to release the parking brake. The parking brake is applied by re
26、leasing the pressure allowing the actuator spring to apply. 3.6 SAER Spring Applied and direct Electrical power Release actuator utilizing the vehicle electrical system or a separate electrical system on the vehicle to release the parking brake. The parking brake is applied by releasing the electric
27、al power allowing the actuator to apply. 3.7 PARKING BRAKE LEVER OR PARKING BRAKE PEDAL A hand or foot operated lever or pedal, which is located within reach of the operator, which transmits force to apply or release the parking brake. 3.8 LEVER LOCK A latch that must be released by the operator bef
28、ore the parking brake lever can be moved to release the parking brake application. 3.9 POWER ASSISTED PARKING BRAKE Actuation of the parking brake is done with the use of an alternate source of mechanical force to apply and release the brake, such as the SAAR, SAHR, and SAER. Copyright SAE Internati
29、onal Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2688 Issued APR2012 Page 4 of 7 4. CONTROL AND INDICATION There are various types of parking brake mechanisms that are utilized on the vehicles outlined in this document
30、 scope. Each requires specific controls to apply and release the parking function. A transmission parking pawl and a mechanical friction parking brake should not be actuated with the same or single actuation device or method. Besides the operator not knowing which parking brake function is actually
31、holding the vehicle, there can be binding and brake release sequence issues with having a single parking actuation function. The following indication designations are for the parking function only. Refer to SAE J915 for indication details for the other transmission (R N D L, etc.) functions. a. Auto
32、matic application and release of a transmission or axle mounted mechanical friction parking brake. i. Indication shall be “PB” and not “P” ii. The designation on the lever, decal or key pad shall be: PB R N D . L (Refer to SAE J915 for other “RND,L” options) iii. Automatic application occurs through
33、 the automatic transmission control lever or key pad. iv. A separate manual actuation method (using a hand or foot operated lever) should not be used in conjunction with this automatic application method. b. Automatic engagement and disengagement of an internal parking pawl in the automatic transmis
34、sion. i. Indication shall be “P” and not “PB”. ii. The designation on the transmission control lever, decal or key pad shall be: P R N D . L (Refer to SAE J915 for other “R N D,L” options) iii. The parking pawl and a mechanical friction parking brake should not be actuated with the same (or single)
35、actuation device. c. Manual application and release of a transmission or axle mounted mechanical friction parking brake using a hand or foot operated lever. i. For transmissions without a parking pawl, the designation on the transmission control lever, decal or key pad shall be:R N D . L (Refer to J
36、915 for other “R N D,L” options) ii. For transmissions with a parking pawl, the designation on the transmission lever, decal or key pad shall be: P R N D . L (Refer to SAE J915 for other R N D,L” options) iii. For a hand operated parking brake lever: 1. To apply parking brake - pull lever to its des
37、igned stroke (not all hand levers are designed to be applied at full stroke). a. Over-center levers operate at full stroke every time. b. Ratchet and pawl levers do not operate at full stroke every time. 2. To release parking brake - disengage optional lever lock and push (return) lever to the relea
38、sed position Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2688 Issued APR2012 Page 5 of 7 iv. For a foot operated parking brake pedal: 1. To apply parking brake - push pedal towards cab floor
39、 a. Repeat as required to engage brake 2. To release parking brake - push/pull the release lever or other release device d. Power assisted application and release of a transmission or axle mounted mechanical friction parking brake using a hand operated mechanical or electrical control device i. For
40、transmissions without a parking pawl, the designation on the transmission lever, decal or key pad shall be: R N D . L (Refer to SAE J915 for other “R N D,L” options) ii. For transmissions with a parking pawl, the designation on the transmission lever, decal or key pad shall be P and not PB: P R N D
41、. L (Refer to SAE J915 for other “R N D,L” options) iii. Hand operated control device is used in conjunction with a mechanical spring apply and either air pressure (SAAR), hydraulic pressure (SAHR) or direct electrical power release (SAER) systems: 1. To apply parking brake - pull device handle or b
42、utton out 2. To release parking brake - push device handle or button in iv. The control device handle or button to be comprised of: 1. Diamond in shape 2. Yellow in color 3. Markings of a. Parking brake b. Push to release c. Pull to apply e. Optional and automatic application devices i. For specific
43、 vehicle vocational applications, the vehicle manufacturer can provide other devices or systems to apply and release the parking brake (example: school bus door interlock system). 5. LOCATION OF CONTROLS Are to be located per the referenced federal and international regulations and practices. 6. CON
44、TROL SYMBOLS Are to be as defined per the referenced federal and international regulations and practices, unless defined in this document. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2688 Is
45、sued APR2012 Page 6 of 7 7. ILLUMINATION AND COLOR OF TELLTALE SYMBOLS Are to be mounted as defined per the referenced federal and international regulations and practices. a. Minimum requirements per federal and international regulations: i. Warning light illuminates when ignition is on and park bra
46、ke is set. ii. If the same light is used for all brake related warnings (except ABS related warnings), the light must read “BRAKE”.iii. If a separate light is used for the park brake warnings the light must read “PARK” as a minimum (additional words may be used). b. Telltale symbols and colors are t
47、o provide the following indications: i. Red “Park Brake“- when the vehicle is parked and ignition is on. 1. Illumination can be immediate or time delayed. 2. An audible device can be used in conjunction with this indicator. ii. Optional Yellow “Apply P/B” if the brake is not applied and the ignition
48、 is off. iii. Optional Yellow “Service P/B” if brake adjustment is required or over-stroke sensor is actuated. 8. OVER-STROKE SENSORS Optional devices to indicate parking brake service as needed. 9. OPTIONAL AUDIBLE DEVICE (BUZZER, CHIME OR EQUIVALENT DEVICE) Shall provide sufficient level of warning to the operator when seated in the drivers seat as well as when the drivers door is open and the driver is out of the vehicle. Sequence of operation shall be: i. “On” when the brake is not applied and the ignition is off. ii. “On” when the brake is on and the vehicle is
